Thanks Onno, Your spectrograms do show the level differences and different spectrums. I spent a day playing with this yesterday, and have managed to demonstrate a couple of microphone effects, and sweep the frequency response.
It's helped me really get my head around microphones, useful for understanding their effect on the codec. Will blog on it later today. Cheers, David On 24/07/15 13:01, Onno Benschop wrote: > Attached is the Audacity spectrogram for each sample. You can discern > differences in frequency response, BUT because the source sound is not > the same, it's non trivial to determine what is variation in sound and > what is variation in response. I don't know exactly what Steve did in > the plots you showed, but I suspect they are subject to the same problem. > > Before figuring out what the difference is between the microphones, I'd > go back a step and see what the codec does to different frequencies. If > you stick a linear sound, like white noise, in and decode it again, I'd > expect to see a linear decoded signal. (Minus what ever you dropped on > the floor by design.) > > To get the same audio into two different microphones is non-trivial. I'd > probably start with a 1 kHz tone in the room and see what it looks like > via the two microphones. > > Damn you, this is too interesting. I want to go out and play with my new > delta-loop. Fortunately I don't have source-code yet, so I cannot > actually play with audio samples and stuff them through the codec ;-) > > On 24 July 2015 at 11:04, Steve <[email protected] > <mailto:[email protected]>> wrote: > > I chose a real fine resolution on the number of FFT bins. Of course > the codec will probably never see all those bins :-) > But I was trying to get a feel for the mics. > > On Thursday, July 23, 2015 at 7:25:55 PM UTC-5, DavidRowe wrote: > > Thanks Tony and Steve, some interesting points. > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > <mailto:[email protected]> > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > > -- > Onno Benschop > > ()/)/)() ..ASCII for Onno.. > |>>? ..EBCDIC for Onno.. > --- -. -. --- ..Morse for Onno.. > > If you need to know: "What computer should I buy?" http://goo.gl/spsb66 > > ITmaze - ABN: 56 178 057 063 - ph: 04 1219 8888 - > [email protected] <mailto:[email protected]> > > > ------------------------------------------------------------------------------ > > > > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
